The IEEE 1394 serial bus is thought of as a network system that enables a transmission of data by isochronous communication and a transmission of a control signal by asynchronous communication between an AV device and an information processing device. The IEEE 1394 serial bus is standardized to “IEEE STD 1394-1995” as “IEEE STANDARD FOR A HIGH PERFORMANCE SERIAL BUS.” As an example of using IEEE 1394 serial buses, Japanese published unexamined patent application No. H08-47058 describes that “a method for selecting input devices” that can display only the identification of a device that is able to output an information signal, as an input available device in a system that is connected to a plurality of electronic devices by way of a communication bus.
Further, an “AV/C Digital Interface Command Set”, which includes control signals to control an AV device for playback and recording of AV data by using a 1394 IEEE serial bus, has been opened to the public by the “1394 Trade Association.” However, in the standard technique for the IEEE 1394 serial bus, in case a plurality of electronic devices perform isochronous communication simultaneously, the available band width and number of channels of the bus are exceeded, and so some of the electronic devices that try to perform communication can not use the bus because of the short available band width and limited number of channels of the bus.
Consider a case wherein, in a network, for example, in which a digital receiver IRD (hereinafter “IRD”) is connected to a device such as a digital videotape recorder D-VTR (hereinafter “D-VTR”), a reserved recording is performed by the network. When the other electronic devices that are connected in the network use the bus during the reserved recording time, and the bus width that the IRD wants to use is larger than the available bus width at that time, the IRD cannot secure the necessary bus width. As a result, the reserved recording cannot be performed because data cannot be satisfactorily transmitted from the IRD to the D-VTR.
Further, in the input device selection method and AV/C Digital Interface Command Set, a method of selecting the input device at the present time, and a method of transmitting the data and the control signals at the present time are only considered.